Harsha - I'm not clear on how your question title accessing empty array element relates to your code. Where are you trying to access an empty element?
If you are concerned with the array size increasing dynamically on each iteration of the loop, then pre-allocate or size the array before entering the loop as
n = 8;
X = zeros(n,1);
Base1 = zeros(n,1);
for k=1:n
X(k) = k;
Base1(k) = k*y*z;
end
It may be that you need to show your outer loops where y and z are initialized. Note how in the above, I have removed the need for the indexing variable r as k can do the same. I use k as MATLAB uses i and j to represent the imaginary number.
